Question

which of the following is not thought to be true of all comets? comets dust & plasma tails always point straight behind them in their orbit all comets from our solar system originated at least beyond jupiters orbit, probably in the kuiper belt or the oort cloud all comets have the composition of a \dirty snowball\ all comets are leftover planetesimals that originally condensed beyond the frost line in the solar nebula

Explanation:

Comets' dust and plasma tails are influenced by the solar wind and radiation pressure. They point away from the Sun, not always straight behind the comet in its orbit. The other statements about comets' origin, composition, and nature as leftover planetesimals are generally accepted facts.

Answer:

Comets' dust & plasma tails always point straight behind them in their orbit